TCP MSS ADJUST ON NCS 5501

[marcinselewki95]

Hi!

I have a question. I want to set tcp mss adjust on specific interface on NCS 5501 router. 

But after write command on interface the error is: "Platfotm doesn't support TCP MSS Adjust on this card. 

Can i do something to turn on the mss adjust?

[balaji.bandi]

I have not seen the configuration guide for MSS, you can only do MTU adjustment 

https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5500/interfaces/63x/b-interfaces-hardware-component-cg-ncs5500-63x/b-interfaces-hardware-component-cg-ncs5500-63x_chapter_0100.html

by the way what interface you trying to adjust this ?

[marcinselewki95]

Thanks for quickly reply.

I try do this on Ethernet interface.

[MHM Cisco World]

MTU can confg in L2/L3 port 

IP MTU can config in L3 port only 
IP TCP MSS can config in L3 port only 

[marcinselewki95]

I try config tcp MSS on L3 interface but it doesn't work.

I can globally set mss using

tcp mss 1410

command. Is this command set mss globally on router?

[Harold Ritter · Accepted solution]

Hi @marcinselewki95 ,

The tcp mss adjust feature is not supported on this platform. The following bug id (CSCvm25963) has been opened but I do not see any progress. Please contact your account team if this feature is required.

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvm25963

Regards,

[marcinselewki95]

Thank to very much @Harold Ritter 

[Harold Ritter]

You are very welcome @marcinselewki95 

[MHM Cisco World]

the tcp mss globally effect the traffic originate from router not traffic bass through router interface. 
so you need to config ip tcp mss in interface. 
@Harold Ritter  mention about bug I think it bug as he mention. 
thanks